Salt, high blood pressure, iodine and soy

April 13, 2013 by VegSteve in Concerns

: naama / Foter.com / CC BY-SA

Cutting back on salt is a very common health recommendation, but for vegetarians and vegans getting too much salt may be less of a concern. According to a 2012 study, vegans had a 63% reduced risk of having high blood pressure, compared to regular meat-eaters, and vegetarians had a 43% reduced risk.

Vegetarians and vegans did so well mainly due to having lower body mass indexes, plus higher potassium intakes, lower insulin levels and (thinner) blood viscosity.

“I have been [vegan and gluten-free] now for about 6 weeks, and I have decided to make it my life. I am loving it so much. … I had my blood pressure checked and it is bang on perfect again.”
– Maria, age 30s, Brampton, ON

Iodine, though, may become an issue for vegetarians, due to the common practice of substituting sea salt for ordinary table salt. Table salt is fortified with iodine. The other dietary sources for iodine are dairy products (due to cow’s teats being washed with an iodine solution), foods grown in soil near the ocean, seaweed and other seafoods.

Iodine is needed for healthy thyroid function which regulates metabolism. Both too much, and too little iodine can result in abnormal thyroid metabolism. According to the UK Vegan Society: “Iodine deficiency during pregnancy and early infancy can result in cretinism (irreversible mental retardation and severe motor impairments)…. Hypothyroidism can manifest as low energy levels, dry or scaly or yellowish skin, tingling and numbness in extremities, weight gain, forgetfulness, personality changes, depression, anaemia, and prolonged and heavy periods in women.” And according to the Mayo Clinic, an overactive or underactive thyroid gland can also lead to hair loss.

There are components in soy, flax seeds, and raw cruciferous vegetables (broccoli, cauliflower, cabbage, etc) that counteract iodine. People who experience thyroid problems from eating soy, may just need extra iodine.

In Canada and the United States, you can get enough iodine from 1/4 teaspoon of iodized salt per day. Note: most packaged foods are made with non-fortified salt. In Europe there is much less iodine in table salt.

Some brands of sea salt are now fortified. Kosher salt contains no iodine. One can also take iodine supplements.

Eating seaweed (multiple times a week), will probably get you adequate iodine. But levels are variable and seaweed can provide too much iodine (iodine toxicity) if eaten in excess, especially for kelp (kombu). Just 15 grams of dried kelp provides a year’s supply for one person. According to the UK Vegan Society: “Consumption of more than 100g/year (by dried weight) of most seaweeds carries a significant risk of thyroid disorder due to iodine intakes in excess of 1000 micrograms per day.” One brand of seaweed, Main Coast, lists iodine content for their kelp to be 2110% of RDA for a 7 gram serving. For their dulse flakes, a 3 gram (one tablespoon) serving equals 330% RDA, meaning a one teaspoon amount is all you should take.

Nori, the seaweed used for sushi, is lower in iodine and several sheets can be eaten per day.